Alternating current electromagnet



March 1, 1938. c. T. EVANS 2,109,741

' ALTERNATING CURRENT ELECTROMAGNET Filed Aug. 51, 1935 i llllI!llllIlllllllllllllIlllllllllllI llIll|llll-IlllllllllllllllllllIlllI Patented Mar. 1, 1938 UNITED STATES I z,1u,m ALTERNATING oUaaaN-r uaoraomomr Clarence T. Evans, Wauwatosa, Wla, anignor to Cutler-Hammer, Inc., Milwaukee, Wis.I a corporatlon of Delaware Application August 31,

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This invention relates to alternating current '10 armatures of ridges which enter the slots in which the shading coils are mounted.

Other objects and advantages of the invention will hereinafter appear.

' The accompanying drawing illustrates an embodiment of the invention which will now be described, it being understood that the embodiment illustrated is susceptible of various modifications without departing from the scope of the appended claims.

In the drawing: v

Figure 1 is a side view of an electromagnet the coil whereof is shown in dotted lines;

Fig. 2 is a front view of that portion of the magnet frame of Fig. l carrying the shading 25 coil;

Fig. 3 is an enlarged side view of the magnetic pole carrying the shading coil, and

Fig. 4 shows the face of the armature member of Fig. 1.

Referring to Fig. 1, the electromagnet shown therein is in general of well known form and hence details thereof have been omitted. It comprises a supporting frame i carrying laminae 2 of magnetic material to form a part of the mag- 35 netic circuit of the coil shown in dotted lines.

Also it comprises an armature member I pivoted to the supporting frame at 5, said armature member carrying laminae 3 of magnetic material to form a part of the magnetic circuit of the afore- 40 mentioned coil.

As shown in Fig. 2 the upper pole of the supporting frame presents a pole face comprising the laminae 2 confined in two groups between a center member 6 and side members I and 8,

45 these members comprising parts of the supporting frame. This pole face is rectangular and at a suitable distance therefrom there is formed in the pole an open slot 9' illustrated in Figs. 1 and 3 and more clearly in the latter view. This slot 50 which extends across the under side of the pole parallel to said pole face is provided to receive a portion of shading coil iii and the pole has cut therein a second slot ll extending through and transversely of its pole face to receive another 55 portion of said shading coil.

1935, Serial No."38,897

The shading coil Ill preferably is formed'of laminae of brass soldered together with a soft solder enabling the laminae to be separated as hereinafter set forth, such a material being now on the market under the trade name Laminum". As' illustrated in Fig. 2 the soldered together laminae are stamped to form a closed loop which as shown is of oblong form, although it is to be understood that the form may be varied as desired. Thus each lamina comprises a complete and unitary closedloop which will be self-sustaining if its soldered connection with adjacent laminae melts or breaks.

Considering now assembly of the shading coil with the magnetic pole, the former after being in part inserted into slot 9 is shifted to eflect its insertion in part into the slot ii. Thereby provision is made for support of the coil which as shown is of such dimensions that it extends beand a similar guard I may be inserted after the coil has been placed. The coil may be secured as desired, but preferably it is secured by a metal retainer [5 inserted into slot II and swedged for retention therein. The retainer preferably extends entirely across the pole face and preferably is swedged substantially throughout its length.

Securement of the coil by a swedged-in retainer as aforedescribed has been found highly advantageous in that the coil may be tightly seated in the slot without strains thereon likely to break the soldered connections of the laminae or to injure the laminae. Unless the coil is securely mounted at least in respect of a. portion thereof it is likely to vibrate to such a degree as to cause breakage thereof. Of course with the coil mounted as illustrated the parts thereof external of the pole as well as the part in slot 9 are subjected to considerable vibration and it has been found in practice that such vibration produces a shear between the laminae of such external parts and that such shearing action aided by the heat of the electromagnet soon breaks the solder bond to free the unconfined portions of the laminae one from another. This, however, is an advantage rather than a disadvantage, for the strains due to vibration are thus reduced to those capable of being set up in the very thin individual lamina and a very thin lamina may very readily be designed to withstand any such strains.

Referring to Fig. 4 showing the face of the armature to engage the slotted pole face hereinbefore discussed, said armature face comprises the laminae-3 confined in two groups between a center member l6 and side members i1 and I8, said members comprising parts of the armature 4. This armature face has a transversely extending slot l9 located therein to register with the slot II in the face of the pole carrying the shading coil. Accordingly it will be impossible for the metal of the armature laminae to build up a ridge capable of entering the slot H and pounding the shading coil as frequently happens where the armature laminations are of usual form.

What I claim as new and desire to secure b Letters Patent is:

1. In an alternating current magnet, a magnet frame having a pole with a slotted face, a shading coil for said pole formed of soldered together laminae, each lamina being unitary and in the form of a closed loop, said coil being passed through said slotted face for assembly with said pole and a retainer for said coil received by said pole through its said slotted face and swedged for securement.

2. In an alternating current magnet, amagnet frame having a pole with a slotted face, a shading coil for said pole formed of soldered together laminae, each lamina being unitary and in the form of a closed loop, said coil having a portion inserted into said pole through said slotted facethereof and having portions outside of said pole' and a retainer for said coil received by said pole through its said slotted face and swedged for securement.

3. In an alternating current magnet, a magnet frame having a pole with a slotted face, a shading coil for said pole formed of soldered together laminae, each lamina comprising a single sheet metal stamping having the form of a thin flat closed loop, said coil having a portion thereof inserted into said pole through the slotted face thereof and having portions external of said pole and means to secure said coil in place leaving the external portions of said coil free for loosening of theif laminae one from another under the influence of the heat and vibration of operation of the magnet.

4. In an alternating current magnet, a magnet frame having a pole provided with two transversely extending slots, one an end face slot and the other a side face slot underlying the end face of said pole, a shading coil for said pole formed of soldered together laminae, each lamina comprising a single sheet metal stamping having the form of a thin fiat closed loop, said coil having a portion thereof insertedinto said side face slot, a portion inserted into said end face slot, and intermediate portions external of said pole, and means to secure said coil in said end face slot.

5. In an alternating current magnet, a magnet frame having a pole with'a slotted end face, a shading coil for said pole having a portion thereof inserted into said end face slot of said pole, a retainer. for said coil extending substantially the full length of said slot and swedged in said slot and an armature member for said frame having a face to engage said end face of said pole, said faces engaging in a single plane and having an area of engagement divided by said pole slot and said face of said armature member being recessed opposite the slot area of. said pole face for protection of the elements within said slot.

CLARENCE T. EVANS. 

